I. Field of the Invention
This invention relates generally to lift and dump mechanisms for lifting and emptying containers, particularly refuse containers, into a multi-compartment refuse vehicle. More particularly, this invention relates to a device and method that automatically lifts, dumps into a selected hopper and returns a container to the same location on the curbside. Position sensitive potentiometers coupled to the container handling mechanism generate signals that allow coordination of the various members of the container handling mechanism for smooth operation and automatic return of the container handling mechanism to an initial position.
II. Discussion of the Related Art
Over the years, various devices have been used to transfer the contents of waste receptacles into the storage bodies of refuse vehicles. Refuse vehicles may load from the front, side or rear. Mechanized material handling devices often include a container holder or grasping device connected to an arm which is connected to a base, such as a vehicle. The arm and grasping device are operated to engage a container of interest, lift and dump the container into a receiving hopper in the vehicle.
A representative example of such a device appears in U.S. Pat. No. 5,391,039, issued to Holtom, which describes a refuse loader arm including a lift limb and a reach limb articulated to one another at a pivot point. The lift limb is vertically pivotally attached at one end to a refuse vehicle and the reach limb is articulated at its other end to a bin grasping assembly which is held at a constant angle to the lift limb by a parallelogram linkage. The lift limb and the reach limb pivot in a common plane to reach out and grasp the container of interest and lift and dump the container. Of course, the vehicle must be positioned directly alongside the container such that the container is aligned with the pivoting plane of the arm. U.S. Pat. No. 5,330,308, issued to Armando et al., describes a refuse container loading device including a tubular support attached to a refuse vehicle, operable to pivot in a horizontal plane. A telescoping arm that pivots vertically is attached to the base and to a bin grasping device that is able to pivot vertically and swivel horizontally.
Similarly, U.S. Pat. No. 4,175,903, issued to Carson, describes an apparatus for picking up containers wherein a boom arm is attached to a platform which is pivotally attached to a refuse vehicle for rotating in a generally horizontal plane. The boom arm is pivotally attached to the platform for pivoting vertically to raise and dump a container. A pick-up arm is provided to grasp the container and is attached to the boom arm with the ability to rotate in essentially a horizontal plane. The devices described in the '308 and '903 patents eliminate the need for precise positioning of the vehicle, but the lift and dump arms are quite complex.
In its simplest form, a fluid-operated actuator system includes a single linear actuator linked to operate on a single machine part. This actuator supplies the force needed to move the part. A jointed arm, for example, usually requires several actuators or a single actuator connected to operate a complex linkage in order to smoothly operate the jointed arm. The jointed arm may be designed using a plurality of actuators coupled in series, the actuation of which must be coordinated in order for the mechanized system to work smoothly. Otherwise, the device may not work as desired, for example, it may jam and even cause severe damage to the mechanical components and other parts of the machine. In this regard a need presently exists for a device and method to improve coordination of such a system. The present invention contemplates coordination of the actuation of fluid operated double acting cylinders coupled in series to a relatively simple lift and dump arm in a manner that avoids jamming and mechanical damage.
The operation of the conventional lift arms and grasping devices often requires that the operator joggle or shake the container above a preselected hopper opening while in the dump position to remove any contents jammed in the container. The operator must then manually control the positioning of the arm and grasping device in order to place the container on the ground. During this manual operation, it may be difficult for the operator to return the container to the exact position from which it was removed. Replacing a container between other objects in close proximity may prove difficult without incidental contact with the other objects or slamming of the container into the ground. Therefore, there is a need for a device and method to automatically and smoothly return a container to its original position after dumping into a multi-compartment vehicle. The present invention addresses these and other needs.